Method for improving paging success ratio in broad bandwith wireless communication system

ABSTRACT

A method for increasing paging success ratio in a broadband wireless communication system, comprises: when a terminal determines that it has moved into an overlapping area of a plurality of paging groups including an original paging group, the terminal initiates a location updating flow to a current serving BS; an anchor paging controller updates location information of the terminal and includes the current serving BS and its adjacent cell BSs in a paging scope; after the location updating initiated in the overlapping area succeeds and before location updating for moving across paging groups succeeds, the terminal monitors a paging message according to paging parameters of the original paging group; and when the anchor paging controller is required to page the terminal, it initiates paging to a plurality of BSs including the current serving BS and its adjacent cell BSs according to the paging parameters of the original paging group.

TECHNICAL FIELD

The present invention relates to a mobile communication technology, andspecifically to a method for increasing paging success ratio in abroadband wireless communication system.

BACKGROUND OF THE RELATED ART

Worldwide interoperability for microwave access (WiMAX) is a newgeneration broadband wireless communication technology. Compared withconventional 3G access technology, WiMAX has advantages such as in highrate, quality of service (QoS), and flexibility.

FIG. 1 is a diagram of the basic network structure of a WiMAX system,which comprises functional modules including a base station (BS), anaccess gateway (AGW), an authenticator functional module, a pagingcontroller, and an authentication authorization accounting (AAA) moduleetc. Wherein, the paging controller and authenticator functional moduleare generally located in the AGW, and the paging controller can beclassified into anchor paging controller and relay paging controlleraccording to its function; the interface between the BS and the AGW orpaging controller is R6 interface, and the interface between the relaypaging controller and the anchor paging controller is R4 interface.

Idle mode is an important power saving mode in a WiMAX system, and whena terminal is in the idle mode, it can sleep in non-monitoring timeslots, so that the endurance of the mobile terminal can be increasedgreatly. In the idle mode, a terminal reports information of the paginggroup to which it currently belongs to the paging controller by variouslocation updating mechanisms. The common location updating mechanismsgenerally include periodical location updating and paging group locationupdating. A terminal in the idle mode needs to perform downlinksynchronization firstly in each monitoring interval, and during thedownlink synchronization, the terminal needs to scan a downlink channeldescription (DCD) message. According to the description in the WiMAXprotocol, if the paging group list in the DCD message does not includethe paging group to which the terminal currently belongs, the terminalconsiders that it has moved across paging groups, and triggers alocation updating flow to report the latest paging group locationinformation to the paging controller. When downlink data addressed tothe terminal is sent to the AGW, the AGW instructs the anchor pagingcontroller to perform paging, and the anchor paging controller mayinstruct, via a relay paging controller, all or part of the BSs in thepaging group to which the terminal belongs send a paging broadcastmessage to the terminal, so as to instruct the terminal to receive thedata upon exiting from the idle mode.

A flow of a terminal entering the idle mode, paging, and exiting fromthe idle mode is specified in detail in a standard of phase 3 by anetwork working group (NWG) subordinate to the WiMAX forum. Accordingthe description in the WiMAX protocol, for a terminal in mobile state,the paging controller may initiate a paging according to information ofthe paging group to which the terminal belongs reported by locationupdating.

FIG. 2 is a schematic diagram illustrating movement of a terminal inidle mode in a WiMAX system. BS1, BS2, and BS3 are managed by a pagingcontroller, where BS1 belongs to paging group 1, BS3 belongs to paginggroup 2, and BS2 belongs to paging group 1 and paging group 2. Theterminal enters the idle mode at BS1, and chooses paging group 1 as itscurrent paging group. When the terminal moves from the coverage of BS1to the coverage of BS2, location updating triggered by paging areaupdating will not be performed since BS2 also belongs to paging group 1;when the terminal moves swiftly from the coverage of BS2 to the coverageof BS3, the terminal under the new BS3 needs to firstly perform downlinksynchronization, receive a DCD message, detect that it has moved acrosspaging groups, and accordingly initiate a location updating flow. Ifpaging of the terminal happens before the terminal performs the newlocation updating flow successfully, there will be a first time pagingfailure for the terminal, and the paging controller has to page theterminal by a subsequent paging retransmission message. In the worstcase, if the paging controller has not received a location updatingmessage from the terminal before paging times are depleted, paging ofthe terminal will fail.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is toprovide a method for increasing paging success ratio in a broadbandwireless communication system, so as to increase the success ratio ofpaging a terminal.

To solve the above technical problem, the present invention provides amethod for increasing paging success ratio in a broadband wirelesscommunication system, comprising the following steps of:

when a terminal determines that the terminal has moved into anoverlapping area of a plurality of paging groups including an originalpaging group, the terminal initiating a location updating flow to acurrent serving base station;

in the location updating flow, an anchor paging controller updatinglocation information of the terminal and including the current servingbase station and adjacent cell base stations thereof in a paging scope;

after the location updating initiated in the overlapping area succeedsand before location updating for moving across paging groups succeeds,the terminal monitoring a paging message according to paging parametersof the original paging group; and

when the anchor paging controller is required to page the terminal, theanchor paging controller initiating paging to a plurality of basestations including the current serving base station and adjacent cellbase stations thereof according to the paging parameters of the originalpaging group.

Furthermore, the above method may also comprise:

in the location updating flow initiated in the overlapping area, theanchor paging controller adding information of paging groups other thanthe original paging group in the plurality of paging groups into thelocation information of the terminal; and

after the location updating initiated in the overlapping area succeedsand before the location updating for moving across paging groupssucceeds, when the anchor paging controller is required to page theterminal, the anchor paging controller initiating paging to basestations in the plurality of paging groups according to the pagingparameters of the original paging group.

Furthermore, the above method may also comprise:

in the location updating flow initiated in the overlapping area, theanchor paging controller adding information for identifying the currentserving base station of the terminal and the adjacent cell base stationsthereof into the location information of the terminal; and

after the location updating initiated in the overlapping area succeedsand before the location updating for moving across paging groupssucceeds, when the anchor paging controller is required to page theterminal, the anchor paging controller initiating paging to the basestation in the original paging group and said adjacent cell basestations according to the paging parameters of the original paginggroup.

Furthermore, the above method may divide into:

(a) the terminal moving from a base station BS_(A) belonging to a paginggroup A to coverage of another base station BS_(AB); if determining thatthe terminal is currently in an overlapping area of the original paginggroup A and a paging group set B including one or more new paging groupsaccording to a monitored downlink broadcast message from the currentserving base station BS_(AB), then the terminal triggering a locationupdating flow;

(b) in the location updating flow, the base station BS_(AB) sending alocation updating request message to the anchor paging controller of theterminal, and after the anchor paging controller receives the locationupdating request message, the anchor paging controller addinginformation of the paging group included in the paging group set B intothe location information of the terminal, while retaining anidentification and paging parameters of the paging group A;

(c) after the location updating initiated in the overlapping areasucceeds and before the terminal initiates the location updating formoving across paging groups and the location updating for moving acrosspaging groups succeeds, the terminal still monitoring the paging messageaccording to the paging parameters of the paging group A, and when theanchor paging controller is required to page the terminal, the anchorpaging controller initiating paging to the base station in the paginggroup A and the base station in the paging group included in the paginggroup set B recorded in the location information of the terminalaccording to the paging parameters of the paging group A.

Furthermore, the above method may also comprise:

in the step (b), adding a parameter of paging group identifications(PGIDs) into the location updating request message sent by the basestation BS_(AB), the parameter including at least the identification ofthe paging group included in the paging group set B, and after theanchor paging controller receives the location updating request message,the anchor paging controller adding the identification of the paginggroup included in the paging group set B into the location informationof the terminal; or

in the step (b), the location updating request message sent by the basestation BS_(AB) not including the identification of paging group B, andwhen the anchor paging controller determines that the base stationBS_(AB) belongs to both the original paging group A and the paging groupset B according to information of paging groups to which the basestation belongs, or when a relay paging controller for deliveringmessages between the base station BS_(AB) and the anchor pagingcontroller determines which paging groups the base station BS_(AB)belongs to and informs the anchor paging controller, the anchor pagingcontroller adding the identification of the paging group included in thepaging group set B into the location information of the terminal.

Furthermore, the above method may divide into:

(a) the terminal moving from a base station BS_(A) belonging to a paginggroup A to coverage of another base station BS_(AB), and if determiningthat the terminal is currently in an overlapping area of a plurality ofpaging groups including the original paging group A according to amonitored downlink broadcast message from the current serving basestation BS_(AB), then the terminal triggering a location updating flow;

(b) in the location updating flow, the base station BS_(AB) sending alocation updating request message to the anchor paging controller of theterminal, and after the anchor paging controller receives the locationupdating request message, the anchor paging controller addinginformation of the base station BS_(AB) and adjacent cell base stationsthereof into the location information of the terminal, while retainingan identification and paging parameters of the paging group A; and

(c) after the location updating initiated in the overlapping areasucceeds and before the terminal initiates the location updating formoving across paging groups and the location updating for moving acrosspaging groups succeeds, the terminal still monitoring the paging messageaccording to the paging parameters of the paging group A, and when theanchor paging controller is required to page the terminal, the anchorpaging controller initiating paging to the base station in the paginggroup A and the adjacent cell base stations of the base station BS_(AB)according to the paging parameters of the paging group A.

Furthermore, the above method may also comprise:

in the step (b), adding a parameter of adjacent cell base stationidentifications (BSIDs) into the location updating request message sentby the base station BS_(AB), the parameter including at least adjacentcell BSIDs of the base station BS_(AB), and after the anchor pagingcontroller receives the location updating request message, the anchorpaging controller adding said adjacent cell BSIDs into the locationinformation of the terminal; or

in the step (b), the location updating request message sent by the basestation BS_(AB) not including adjacent cell BSIDs of the base stationBS_(AB), and when the anchor paging controller acquires the adjacentcell BSIDs of the base station BS_(AB) by searching according to atopological relationship of base stations, or when a relay pagingcontroller for delivering messages between the base station BS_(AB) andthe anchor paging controller acquires the adjacent cell BSIDs of thebase station BS_(AB) by searching and informs the anchor pagingcontroller, the anchor paging controller adding the identification ofthe base station BS_(AB) and the adjacent cell BSIDs thereof into thelocation information of the terminal.

Furthermore, the above method may also comprise:

when the terminal moves into coverage of another base station, theterminal monitoring a downlink broadcast message from the currentserving base station, and if determining that there are identificationsof a plurality of paging groups including the original paging group in apaging group list in the downlink broadcast message, then determiningthat the terminal is currently in an overlapping area of a plurality ofpaging groups including a paging group A, and then triggering a locationupdating flow actively.

Furthermore, the above method may also comprise:

after moving from said overlapping area to coverage of a base stationnot belonging to the original paging group, the terminal initiating alocation updating flow for moving across paging groups, and in thelocation updating flow, the anchor paging controller updating the paginggroup and paging parameters of the terminal with the paging group towhich the current serving base station belongs and paging parametersthereof; and

after the location updating succeeds, the terminal monitoring the pagingmessage according to the paging parameters of the new paging group, andwhen the anchor paging controller pages the terminal, the anchor pagingcontroller initiating paging to the base station in the new paging groupaccording to the paging parameters of the new paging group.

Furthermore, the above method may have the following features:

when the anchor paging controller pages the terminal, the paging messageis sent in a single step in which a part of the base stations in thepaging scope are paged at one time, or the paging message is sent inmultiple steps in which all base stations in the paging scope are pagedat one time.

Furthermore, the above method may have the following features: thelocation updating flow triggered by the terminal in the overlapping areadivides into the following steps of:

the terminal sending a ranging message to the current serving basestation, and triggering the location updating flow;

after receiving the ranging message, the current serving base stationsending a location updating request message to the anchor pagingcontroller directly or via a relay paging controller;

after receiving the location updating request message, the anchor pagingcontroller returning a location updating response message to the currentserving base station directly or via the relay paging controller,updating the location information of the terminal, and including thecurrent serving base station and the adjacent cell base stations thereofin the paging scope, while retaining the identification and pagingparameters of the original paging group of the terminal;

after receiving the location updating response message, the currentserving base station returning a location updating acknowledgmentmessage to the anchor paging controller, and returning a result of thelocation updating to the terminal through a ranging response message.

Furthermore, the above method may have the following features: themethod is applied in a worldwide interoperability for microwave access(WiMAX) system.

In the technical scheme of the present invention, the location of theterminal is tried to be determined in advance, and each time theterminal is in a overlapping area of paging groups, an updating flow istriggered and location updating is performed, which ensures that thepaging parameters at the network side can be updated timely and thusincreases greatly the success ratio of paging the terminal, and furtherensures the reliability of the paging scope and avoids a pagingbroadcast storm caused by paging in a too large area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of the basic network structure of a WiMAX system inthe prior art;

FIG. 2 is a schematic diagram illustrating movement of a terminal inidle mode in a WiMAX system in the prior art;

FIG. 3 is a flow chart of preferred embodiment 1 of the presentinvention;

FIG. 4 is a flow chart of preferred embodiment 2 of the presentinvention.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

Preferred embodiments of the present invention will be described indetail with reference to FIG. 3 and FIG. 4 and in conjunction with thescenario shown in FIG. 2.

A terminal in idle mode moves gradually from the coverage of BS1 to theoverage of BS2 (within the overlapping area of paging group 1 and paginggroup 2, and also a border area of paging group 1), and then moves fromthe coverage of BS2 to the overage of BS3. In order to increase pagingsuccess ratio, a possible location of the terminal is tried to bedetermined in advance, and paging is implemented on the premise that thelocation updating flow and paging flow will not be affected.

The method for increasing paging success ratio in a broadband wirelesscommunication system provided by the present invention includes twopreferred embodiments.

Embodiment 1

With reference to FIG. 3, in this embodiment, paging groupidentifications (PGIDs) are utilized to determine the current locationof a terminal, and corresponding location updating is performed.

Step S301, a terminal enters the idle mode in the coverage of BS1,chooses the BS1 as the current serving BS of the terminal, performsdownlink synchronization, and receives a DCD message; a pagingcontroller designates the terminal to belong to paging group 1currently, and designates corresponding paging parameters including atleast a paging cycle (PAGEING_CYCLE), a paging offset (PAGING OFFSET),and a paging interval length;

Under the BS1, the terminal only finds the PGID of the paging group 1 inthe DCD message, thus the terminal does not trigger a location updatingflow.

Step S302, when moving into the coverage of BS2, the terminal monitors adownlink broadcast message, and if the terminal determines that it hasentered the overlapping area of two paging groups, the terminalinitiates a location updating flow to the BS2, and the BS2 reportsinformation of the paging group 2 to the anchor paging controller of theterminal;

After moving into the coverage of the BS2, the terminal sets the servingBS to the BS2, and wakes up in a paging monitoring interval to monitor adownlink broadcast message. Before starting the monitoring, the terminalneeds to firstly perform downlink synchronization and receive a DCDmessage, and if there is the PGID of paging group 1 and a PGID of otherpaging group in a paging group list in the DCD message, the terminalconsiders that it is at the border area of paging areas, that is, theterminal is in the overlapping area of the paging group 1 and paginggroup 2, since the PGID of the paging group 2 does not belong to thepaging group 1 to which the terminal belongs currently. Of course, a BSmay acquire information of the paging group to which the BS2 belongsfrom other downlink broadcast message such as MOB-NBR-ADV or MOB-PAG-ADVmessage.

Then the terminal may trigger a location updating flow actively, or maytrigger a location updating flow periodically by a location updatingtimer (the former way is recommended). The terminal may trigger locationupdating by a ranging message.

After receiving the ranging message, the BS2 sends a location updatingrequest message (R6 interface location updating request message) to theanchor paging controller of the terminal, where the location updatingrequest message contains information of the paging group 2 (includingthe PGID of the paging group 2), and the R6 interface location updatingrequest message used in this embodiment is shown in table 1. A parameter“PGIDs” (paging group identifications) is added into the originallocation updating request to indicate the paging group to which theterminal belongs currently. Since the original parameter “PagingInformation” in the message can indicate information of paging group 1,the newly added parameter “PGIDs” may only include the identification ofpaging group 2, i.e., it may not include the paging group to which theterminal belongs. Of course, the newly added parameter “PGIDs” mayinclude both the identification of paging group 1 and that of paginggroup 2.

TABLE 1 R6 interface location updating request message Required/Parameters Description Optional Interpretation BS ID Base stationRequired Indicating the identification identification of the basestation where the terminal performs location updating PGIDs Paging groupOptional Paging group identifications identifications of the basestation where the terminal performs location updating (the paging groupto which the terminal belongs is not included) Anchor PC ID Anchorpaging Required The anchor paging controller controller identificationcarried in air identification interface unregistering request messageAuthentication Indication of whether the Required 0: no authenticationIndication source base station has information security information for1: having authentication checking RNG-REQ message information Anchor PCAnchor paging controller Optional Identification of the anchorRelocation that requests updating paging controller required toDestination be relocated Paging Paging information Optional The pagingparameters include: Information PAGING_CYCLE, PAGING OFFSET and PagingGroup ID. The base station may provide recommended values for the pagingcycle and paging offset of the terminal. Network Exit This parameterindicates Optional This parameter is used for Indicator that theterminal is shut-down location updating. currently shutting down.

If there is no direct physical link connecting the BS2 and the anchorpaging controller, the BS2 has to send location updating requestmessages to the anchor paging controller via the relay pagingcontroller, and those location updating request messages include a R4interface location updating request message and a R6 interface locationupdating request message. Wherein, content of the R6 interface locationupdating request message is shown in table 1 and content of the R4interface location updating request message is shown in table 2. Theparameter “PGIDs” is also added into the R4 interface location updatingrequest message, it includes the identification of paging group 2, andmay certainly also include the identification of paging group 1.

TABLE 2 R4 interface location updating request message Required/Parameters Description Optional Interpretation BS ID Base stationRequired Indicating the identification identification of the basestation where the terminal performs location updating PGIDs Paging groupOptional Paging group identifications identifications of the basestation where the terminal performs location updating (the paging groupto which the terminal belongs is not included) Anchor PC Anchor pagingcontroller Optional Identification of the anchor Relocation thatrequests updating paging controller required to Destination be relocatedPaging Paging information Optional The paging parameters include:Information PAGING_CYCLE, PAGING OFFSET and Paging Group ID. The basestation may provide recommended values for the paging cycle and pagingoffset of the terminal. Network Exit This parameter indicates OptionalThis parameter is used for Indicator that the terminal is shut-downlocation updating. currently shutting down.

Note that the parameter PGIDs may not be added into the above R6 and R4interface location updating request messages, and in that case, theanchor paging controller or the relay paging controller is required torecord a corresponding relationship between the BS and the paginggroups. As such, the anchor paging controller or the relay pagingcontroller may acquire the paging groups to which the BS2 belongs, i.e.paging group 1 and paging group 2, by searching according to the BS2that reports the location updating message, and may then determine thatthe terminal has moved into the overlapping area of paging group 1 andpaging group 2. Accordingly, the anchor paging controller may add thePGID of the paging group 2 into the paging group information in thelocation information of the terminal. Herein, if the determination ismade by the relay paging controller, the relay paging controller needsto inform the anchor paging controller of the information of the paginggroup 2 such as the identification of paging group 2.

Step S303, after receiving the location updating request message, theanchor paging controller adds the identification of paging group 2 inthe parameter PGIDs of the location updating request message into thepaging group information in the location information of the terminal,while keeping the paging group to which the terminal belongs and thepaging parameters unchanged, and then returns a location updatingresponse message to the BS2 directly or via the relay paging controller;

When the terminal moves into the coverage of BS2, as the terminal hasnot left the paging group 1, the location updating at the network sidewill not change the fact that the terminal currently belongs to thepaging group 1, but only adds the identification of the paging group 2into the location information of the terminal to assist locating. Theterminal still belongs to the paging group 1, and the paging parametersof the terminal are unchanged. If the location updating fails, thepaging controller will do nothing but return a location updating failureresponse, and waits for a next location updating flow.

Step S304, after receiving the location updating response message, theBS2 returns a location updating acknowledgment message to the anchorpaging controller directly or via the relay paging controller, andreturns a result of the location updating to the terminal through aranging response message at the air interface;

Step S305, the terminal leaves the BS2 and moves into the coverage ofBS3, then it enters the coverage of paging group 2, and triggers alocation updating flow for moving across paging groups;

After moving into the coverage of the BS3, the terminal performsdownlink synchronization and receives a DCD message from the BS3. If thePGID of the paging group 1 is not found in the DCD message, which onlyincludes the identification of the paging group 2, it indicates theterminal has left the paging group 1 and already moved across paginggroups, then the terminal will trigger a location updating flow formoving across paging groups. The location updating flow is the same asthat in the current standard, and the original standard message may beused. In the flow, the anchor paging controller updates the paging groupto which the terminal belongs and the paging parameters with the paginggroup 2 and paging parameters of paging group 2, and meanwhile deletesinformation of paging group 1. The specific process of the flow isomitted here for simplicity.

After the location updating initiated by the terminal under the BS2succeeds, and before the location updating for moving across paginggroups initiated by the terminal under the BS3 succeeds, when the AGWreceives data addressed to the terminal, the AGW instructs, by aninternal message, the anchor paging controller of the terminal toinitiate a paging flow, and the anchor paging controller sends a pagingmessage to BSs in paging group 1 and paging group 2 respectivelyaccording to the identifications of the two paging groups recorded inthe location information of the terminal. Since the terminal stillbelongs to paging group 1, the anchor paging controller still uses thepaging parameters of paging group 1 to send the paging message. At theterminal side, since the location updating initiated by the terminalafter moving into the coverage of BS2 did not change the paging group towhich the terminal belongs, the terminal still monitors a paging messageunder the BS2 or BS3 according to the paging parameters of paging group1 before the location updating for moving across paging groups succeeds.Thus, even though the terminal has entered the coverage of BS3, it canstill be paged successfully, and thereby the paging success ratio isimproved.

In particular, the paging message (may be a broadcast message) may besent in a single step or multiple steps. When it is sent in a singlestep, the paging controller sends the page message at one time to allthe BSs in the paging groups recorded. When it is sent in multiplesteps, the paging controller sends the paging message at multiple timesto the BSs in the paging groups recorded. After receiving the pagingmessage from the paging controller, the BSs send the paging message atair interfaces according to the paging parameters indicated by thepaging controller. In this process, if the paging controller receives apaging access message from the terminal, it no more sends a pagingmessage in subsequent process.

The terminal exits from the idle mode and starts a paging access flow ifthe paging broadcast message indicates that it is paged.

Step S306, after the location updating for moving across paging groupssucceeds, when the anchor paging controller needs to page the terminal,it sends a paging message to the BSs in the paging group 2 according topaging parameters of the paging group 2, and the terminal monitors thepaging message under BS3 according to the paging parameters of thepaging group 2.

The processing then is consistent with the current standard, and willnot be repeated here.

Embodiment 2

With reference to FIG. 4, in this embodiment, a BS reports adjacent cellBS identifications (BSIDs) after initiating location updating at theborder area of paging groups, and when an anchor paging controller needsto page a terminal, it sends a paging message to the BS where theterminal is located and its adjacent cell BSs.

Step S401, a terminal enters the idle mode under BS1, and chooses theBS1 as its preferred BS; the terminal can perform downlinksynchronization and receive a DCD message in the coverage of the BS1,and a paging controller designates the terminal to belong to paginggroup 1 currently and designates corresponding paging parameters;

Step S402, when the terminal moves into the coverage of BS2, theterminal monitors a downlink broadcast message, and if it determinesthat it has entered an overlapping area of two paging groups, theterminal initiates a location updating flow to the BS2; then the BS2reports information of adjacent cell BSs to the anchor paging controllerof the terminal;

Similarly, the terminal may determine that it has entered theoverlapping area of two paging groups according to the paging groupidentifications in the DCD message, and thus trigger a location updatingflow.

When performing location updating for the terminal, the BS2 sends a R6interface location updating request message to the anchor pagingcontroller. The R6 interface location updating request message is shownin table 3, in which a parameter, namely adjacent cell BSidentifications (BSIDs) of the BS where the terminal performs locationupdating, which is identifications of BS1 and BS3 herein, is added. Theidentification of BS2 has been defined in the message.

TABLE 3 R6 interface location updating request message Required/Parameters Description Optional Interpretation BS ID Base stationRequired Indicating the identification identification of the basestation where the terminal performs location updating AdjacentIdentifications of Optional Identifications of adjacent Cell BSIDsadjacent cell BSs cell BSs of the BS where the terminal performslocation updating Anchor PC ID Anchor paging controller Required Theanchor paging controller identification identification carried in airinterface unregistering request message Authentication Indication ofwhether the Required 0: no authentication Indication source base stationhas information security information for 1: having authenticationchecking RNG-REQ message information Anchor PC Anchor paging controllerOptional Identification of the anchor Relocation that requests updatingpaging controller required to Destination be relocated Paging Paginginformation Optional The paging parameters include: InformationPAGING_CYCLE, PAGING OFFSET and Paging Group ID. The base station mayprovide recommended values for the paging cycle and paging offset of theterminal. Network Exit This parameter indicates Optional This parameteris used for Indicator that the terminal is shut-down location updating.currently shutting down.

If there is no direct physical link connecting the BS2 and the anchorpaging controller, the BS2 may send location updating request messages,including a R4 interface location updating request message and a R6interface location updating request message, to the anchor pagingcontroller via a relay paging controller. The content of the R6interface location updating request message is shown in table 3, and thecontent of the R4 interface location updating request message is shownin table 4, into which adjacent cell BSIDs of the BS where the terminalperforms location updating is also added.

TABLE 4 R4 interface location updating request message Required/Parameter Description Optional Interpretation BS ID Base stationRequired Indicating the identification identification of the basestation where the terminal performs location updating AdjacentIdentifications of Optional Identifications of adjacent Cell BSIDsadjacent cell BSs cell BSs of the BS where the terminal performslocation updating Anchor PC Anchor paging controller OptionalIdentification of the anchor Relocation that requests updating pagingcontroller required to Destination be relocated Paging Paginginformation Optional The paging parameters include: InformationPAGING_CYCLE, PAGING OFFSET and Paging Group ID. The base station mayprovide recommended values for the paging cycle and paging offset of theterminal. Network Exit This parameter indicates Optional This parameteris used for Indicator that the terminal is shut-down location updating.currently shutting down.

Note that the parameter adjacent cell BSIDs may not be added into the R6and R4 interface location updating request messages, and in that case,the anchor paging controller or relay paging controller is required torecord a topological relationship of BSs. As such, the anchor pagingcontroller or relay paging controller may acquire the adjacent cell BSsof BS2 by searching according to the BS2 that reports the locationupdating message, and accordingly the anchor paging controller may addthe identifications of the adjacent cell BSs into the locationinformation of the terminal. Herein, if the relay paging controlleracquires the adjacent cell BSs of BS2, the relay paging controller needsto notify the anchor paging controller of the adjacent cell BSIDs.

Step S403, after receiving the location updating request message, theanchor paging controller adds the identification of the BS2 and theidentifications of adjacent cell BSs of the BS2 into the locationinformation of the terminal, while keeping the paging group to which theterminal belongs and the paging parameters unchanged, and returns alocation updating response message to the BS2 directly or via the relaypaging controller;

When the terminal moves into the coverage of the BS2, the locationupdating at network side does not change the paging group to which theterminal currently belongs since the terminal has not left paging group1, but only adds the identifications of the BS2 and its adjacent cellBSs into the location information of the terminal to assist locating.The terminal still belongs to the paging group 1, and the pagingparameters of the terminal are unchanged. The location information ofthe terminal may include information of the paging group to which theterminal belongs, the BS where the terminal is located, and informationof the adjacent cells etc.

Step S404, after receiving the location updating response message, theBS2 returns a location updating acknowledgment message to the anchorpaging controller directly or via the relay paging controller, andreturns a result of the location updating to the terminal through aranging response message at the air interface;

Step S405, the terminal leaves the BS2 and moves into the coverage ofBS3, then enters the coverage of paging group 2, and triggers a locationupdating flow for moving across paging groups;

Similarly, the terminal may determine that it has moved across paginggroups according to the PGID in the DCD message from BS3. The locationupdating flow for moving across paging groups may be the same as thecurrent standard. In the flow, the anchor paging controller may updatethe paging group to which the terminal belongs and the paging parameterswith the paging group 2 and paging parameters of paging group 2, and mayalso update the identification of the BS where the terminal is locatedand the identifications of the adjacent cell BSs in the locationinformation of the terminal

After the location updating initiated by the terminal under BS2succeeds, and before the location updating for moving across paginggroups initiated by the terminal under BS3 succeeds, when the AGWreceives data addressed to the terminal, it instructs, by an internalmessage, the anchor paging controller of the terminal to initiate apaging flow, and the anchor paging controller sends a paging message toat least the BS where the terminal is located and the adjacent cell BSs,using paging parameters of paging group 1. The terminal still monitorsthe paging message under the BS2 or BS3 according to paging parametersof paging group 1. Therefore, even though the terminal has entered thecoverage of the BS3, it can still be paged successfully, and therebypaging success ratio is increased.

The above processing can be regarded as temporarily extending the BSsincluded in the paging group 1 by adding the BS3 into the paging group1, for the terminal. As such, the terminal can be paged successfully. Asdescribed above, the paging can be implemented in a single step ormultiple steps. If it is implemented in a single step, the pagingmessage should be sent to all the BSs in the paging group 1 and the BS3;and if it is implemented in multiple steps, the paging message may besent to the BS where the terminal is located and the adjacent cell BSsin the first step.

Step S406, after the location updating for moving across paging groupssucceeds, when the anchor paging controller needs to page the terminal,it sends a paging message to the BSs in the paging group 2 according topaging parameters of the paging group 2, and the terminal monitors thepaging message under the BS3 according to the paging parameters of thepaging group 2.

Industrial Applicability

The present invention implements location updating at the network sideby determining in advance the location of the terminal. Each time theterminal is in the overlapping area of paging groups, an updating flowis triggered and location updating is performed. Thereby, success ratioof paging the terminal is increased greatly and reliability of thepaging scope is ensured as well.

1. A method for increasing paging success ratio in a broadband wireless communication system, comprising the following steps of: when a terminal determines that the terminal has moved into an overlapping area of a plurality of paging groups including an original paging group, the terminal initiating a location updating flow to a current serving base station; in the location updating flow, an anchor paging controller updating location information of the terminal and including the current serving base station and adjacent cell base stations thereof in a paging scope; after the location updating initiated in the overlapping area succeeds and before location updating for moving across paging groups succeeds, the terminal monitoring a paging message according to paging parameters of the original paging group; and when the anchor paging controller is required to page the terminal, the anchor paging controller initiating paging to a plurality of base stations including the current serving base station and adjacent cell base stations thereof according to the paging parameters of the original paging group.
 2. The method according to claim 1, further comprising: in the location updating flow initiated in the overlapping area, the anchor paging controller adding information of paging groups other than the original paging group in the plurality of paging groups into the location information of the terminal; and after the location updating initiated in the overlapping area succeeds and before the location updating for moving across paging groups succeeds, when the anchor paging controller is required to page the terminal, the anchor paging controller initiating paging to base stations in the plurality of paging groups according to the paging parameters of the original paging group.
 3. The method according to claim 2, wherein the method divides into the following steps of: (a) the terminal moving from a base station BS_(A) belonging to a paging group A to coverage of another base station BS_(AB); if determining that the terminal is currently in an overlapping area of the original paging group A and a paging group set B including one or more new paging groups according to a monitored downlink broadcast message from the current serving base station BS_(AB), then the terminal triggering a location updating flow; (b) in the location updating flow, the base station BS_(AB) sending a location updating request message to the anchor paging controller of the terminal, and after the anchor paging controller receives the location updating request message, the anchor paging controller adding information of the paging group included in the paging group set B into the location information of the terminal, while retaining an identification and paging parameters of the paging group A; (c) after the location updating initiated in the overlapping area succeeds and before the terminal initiates the location updating for moving across paging groups and the location updating for moving across paging groups succeeds, the terminal still monitoring the paging message according to the paging parameters of the paging group A, and when the anchor paging controller is required to page the terminal, the anchor paging controller initiating paging to the base station in the paging group A and the base station in the paging group included in the paging group set B recorded in the location information of the terminal according to the paging parameters of the paging group A.
 4. The method according to claim 3, further comprising: in the step (b), adding a parameter of paging group identifications (PGIDs) into the location updating request message sent by the base station BS_(AB), the parameter including at least the identification of the paging group included in the paging group set B, and after the anchor paging controller receives the location updating request message, the anchor paging controller adding the identification of the paging group included in the paging group set B into the location information of the terminal; or in the step (b), the location updating request message sent by the base station BS_(AB) not including the identification of paging group B, and when the anchor paging controller determines that the base station BS_(AB) belongs to both the original paging group A and the paging group set B according to information of paging groups to which the base station belongs, or when a relay paging controller for delivering messages between the base station BS_(AB) and the anchor paging controller determines which paging groups the base station BS_(AB) belongs to and informs the anchor paging controller, the anchor paging controller adding the identification of the paging group included in the paging group set B into the location information of the terminal.
 5. The method according to claim 3, wherein the location updating flow triggered by the terminal in the overlapping area divides into the following steps of: the terminal sending a ranging message to the current serving base station, and triggering the location updating flow; after receiving the ranging message, the current serving base station sending a location updating request message to the anchor paging controller directly or via a relay paging controller; after receiving the location updating request message, the anchor paging controller returning a location updating response message to the current serving base station directly or via the relay paging controller, updating the location information of the terminal, and including the current serving base station and the adjacent cell base stations thereof in the paging scope, while retaining the identification and paging parameters of the original paging group of the terminal; after receiving the location updating response message, the current serving base station returning a location updating acknowledgment message to the anchor paging controller, and returning a result of the location updating to the terminal through a ranging response message.
 6. The method according to claim 2, further comprising: when the terminal moves into coverage of another base station, the terminal monitoring a downlink broadcast message from the current serving base station, and if determining that there are identifications of a plurality of paging groups including the original paging group in a paging group list in the downlink broadcast message, then determining that the terminal is currently in an overlapping area of a plurality of paging groups including a paging group A, and then triggering a location updating flow actively.
 7. The method according to claim 2, further comprising: after moving from said overlapping area to coverage of a base station not belonging to the original paging group, the terminal initiating a location updating flow for moving across paging groups, and in the location updating flow, the anchor paging controller updating the paging group and paging parameters of the terminal with the paging group to which the current serving base station belongs and paging parameters thereof; and after the location updating succeeds, the terminal monitoring the paging message according to the paging parameters of the new paging group, and when the anchor paging controller pages the terminal, the anchor paging controller initiating paging to the base station in the new paging group according to the paging parameters of the new paging group.
 8. The method according to claim 2, wherein, when the anchor paging controller pages the terminal, the paging message is sent in a single step in which a part of the base stations in the paging scope are paged at one time, or the paging message is sent in multiple steps in which all base stations in the paging scope are paged at one time.
 9. The method according to claim 2, wherein the method is applied in a worldwide interoperability for microwave access (WiMAX) system.
 10. The method according to claim 1, further comprising: in the location updating flow initiated in the overlapping area, the anchor paging controller adding information for identifying the current serving base station of the terminal and the adjacent cell base stations thereof into the location information of the terminal; and after the location updating initiated in the overlapping area succeeds and before the location updating for moving across paging groups succeeds, when the anchor paging controller is required to page the terminal, the anchor paging controller initiating paging to the base station in the original paging group and said adjacent cell base stations according to the paging parameters of the original paging group.
 11. The method according to claim 10, wherein the method divides into the following steps of: (a) the terminal moving from a base station BS_(A) belonging to a paging group A to coverage of another base station BS_(AB), and if determining that the terminal is currently in an overlapping area of a plurality of paging groups including the original paging group A according to a monitored downlink broadcast message from the current serving base station BS_(AB), then the terminal triggering a location updating flow; (b) in the location updating flow, the base station BS_(AB) sending a location updating request message to the anchor paging controller of the terminal, and after the anchor paging controller receives the location updating request message, the anchor paging controller adding information of the base station BS_(AB) and adjacent cell base stations thereof into the location information of the terminal, while retaining an identification and paging parameters of the paging group A; and (c) after the location updating initiated in the overlapping area succeeds and before the terminal initiates the location updating for moving across paging groups and the location updating for moving across paging groups succeeds, the terminal still monitoring the paging message according to the paging parameters of the paging group A, and when the anchor paging controller is required to page the terminal, the anchor paging controller initiating paging to the base station in the paging group A and the adjacent cell base stations of the base station BS_(AB) according to the paging parameters of the paging group A.
 12. The method according to claim 11, further comprising: in the step (b), adding a parameter of adjacent cell base station identifications (BSIDs) into the location updating request message sent by the base station BS_(AB), the parameter including at least adjacent cell BSIDs of the base station BS_(AB), and after the anchor paging controller receives the location updating request message, the anchor paging controller adding said adjacent cell BSIDs into the location information of the terminal; or in the step (b), the location updating request message sent by the base station BS_(AB) not including adjacent cell BSIDs of the base station BS_(AB), and when the anchor paging controller acquires the adjacent cell BSIDs of the base station BS_(AB) by searching according to a topological relationship of base stations, or when a relay paging controller for delivering messages between the base station BS_(AB) and the anchor paging controller acquires the adjacent cell BSIDs of the base station BS_(AB) by searching and informs the anchor paging controller, the anchor paging controller adding the identification of the base station BS_(AB) and the adjacent cell BSIDs thereof into the location information of the terminal.
 13. The method according to claim 11, wherein the location updating flow triggered by the terminal in the overlapping area divides into the following steps of: the terminal sending a ranging message to the current serving base station, and triggering the location updating flow; after receiving the ranging message, the current serving base station sending a location updating request message to the anchor paging controller directly or via a relay paging controller; after receiving the location updating request message, the anchor paging controller returning a location updating response message to the current serving base station directly or via the relay paging controller, updating the location information of the terminal, and including the current serving base station and the adjacent cell base stations thereof in the paging scope, while retaining the identification and paging parameters of the original paging group of the terminal; after receiving the location updating response message, the current serving base station returning a location updating acknowledgment message to the anchor paging controller, and returning a result of the location updating to the terminal through a ranging response message.
 14. The method according to claim 10, further comprising: when the terminal moves into coverage of another base station, the terminal monitoring a downlink broadcast message from the current serving base station, and if determining that there are identifications of a plurality of paging groups including the original paging group in a paging group list in the downlink broadcast message, then determining that the terminal is currently in an overlapping area of a plurality of paging groups including a paging group A, and then triggering a location updating flow actively.
 15. The method according to claim 10, further comprising: after moving from said overlapping area to coverage of a base station not belonging to the original paging group, the terminal initiating a location updating flow for moving across paging groups, and in the location updating flow, the anchor paging controller updating the paging group and paging parameters of the terminal with the paging group to which the current serving base station belongs and paging parameters thereof; and after the location updating succeeds, the terminal monitoring the paging message according to the paging parameters of the new paging group, and when the anchor paging controller pages the terminal, the anchor paging controller initiating paging to the base station in the new paging group according to the paging parameters of the new paging group.
 16. The method according to claim 10, wherein, when the anchor paging controller pages the terminal, the paging message is sent in a single step in which a part of the base stations in the paging scope are paged at one time, or the paging message is sent in multiple steps in which all base stations in the paging scope are paged at one time.
 17. The method according to claim 10, wherein the method is applied in a worldwide interoperability for microwave access (WiMAX) system.
 18. The method according to claim 1, further comprising: when the terminal moves into coverage of another base station, the terminal monitoring a downlink broadcast message from the current serving base station, and if determining that there are identifications of a plurality of paging groups including the original paging group in a paging group list in the downlink broadcast message, then determining that the terminal is currently in an overlapping area of a plurality of paging groups including a paging group A, and then triggering a location updating flow actively.
 19. The method according to claim 1, further comprising: after moving from said overlapping area to coverage of a base station not belonging to the original paging group, the terminal initiating a location updating flow for moving across paging groups, and in the location updating flow, the anchor paging controller updating the paging group and paging parameters of the terminal with the paging group to which the current serving base station belongs and paging parameters thereof; and after the location updating succeeds, the terminal monitoring the paging message according to the paging parameters of the new paging group, and when the anchor paging controller pages the terminal, the anchor paging controller initiating paging to the base station in the new paging group according to the paging parameters of the new paging group.
 20. The method according to claim 1, wherein, when the anchor paging controller pages the terminal, the paging message is sent in a single step in which a part of the base stations in the paging scope are paged at one time, or the paging message is sent in multiple steps in which all base stations in the paging scope are paged at one time.
 21. The method according to claim 1, wherein the method is applied in a worldwide interoperability for microwave access (WiMAX) system. 